1. Field of the Invention
The present invention relates to a coupling, more specifically to a torque-limiting coupling.
2. Description of the Prior Art
A torque-limiting coupling is adapted for preventing damage of fastener or threaded hole by excessive torque provided by a pneumatic tool or other tools.
A conventional torque-limiting coupling has a torque-limiting assembly forming a groove and a limiting mechanism forming an opening. The opening is inserted by a fastener. However, force of rotation of a pneumatic tool is quite large, and part of force is distributed to the fastener to result abrasion of the fastener and the wall of the groove. Thus, the fastener is difficult to be accurately disposed into the groove, and deviation is thereby resulted.
Another kind of torque-limiting coupling has an elastic element sleeved onto a driving axle and is located between a plate and an adjusting element. However, the plate and the driving axle are formed integrally, so the plate is not pushed by the elastic element and is shifted toward the pneumatic tool when the torque reaches the limitation. Thus, user's hands are discomfortable due to the shock.
The present invention is, therefore, arisen to obviate or at least mitigate the above mentioned disadvantages.